Module Method Definition problem

[embooglement]

I'm developing a mass aggregate physics engine with RMXP. One of the components is the module that follows:

#=============================================================================

#-----------------------------------------------------------------------------

# ** Spring_Physics

#-----------------------------------------------------------------------------

#=============================================================================

module Spring_Physics

  #---------------------------------------------------------------------------

  # This module defines physics constants for spring physic objects

  #---------------------------------------------------------------------------

  G = 1.0    # Gravity

  K = 0.025  # Spring Constant

  D = 0.95   # Dampening

  R = 25.0   # Rest Length

  #---------------------------------------------------------------------------

  # * Point_Direction

  # Returns the radian angle of the line formed between the two points.

  #---------------------------------------------------------------------------

  def point_direction(x1, y1, x2, y2)

    r = (x1 - x2) / (y1 - y2)

    r *= Math::PI/4

    return r

  end

end

One thing to note, I'm not entirely sure if my conversion of a slope to radian measure is even remotely accurate. But alas, that is not my problem.

As it is, when I try to call Spring_Physics.point_direction() I get an error saying " undefined method for `point_direction' for Spring_Physics:module ".

I'm desperately confused. Admittedly, I haven't defined any modules before, but from everything I can tell, this should work. Anyone have any suggestions?

And while I'm at it, anyone know the way to take a line defined by two points and get the radian angle formed by them?

Any help would be greatly appreciated!

 

[BwdYeti]

Change the method definition to [rgss]def self.point_direction(x1, y1, x2, y2)
[/rgss]
I don't exactly know why you have to do that, so someone more knowledgeable would need to explain.

 

[SephirothSpawn]

def blah in a module is just an instance method. These methods are really only ever used when you include a module into a class or other module.

module Test

  def blah

    p rand(3)

  end

end

 

class Test2

  include Test

end

 

a = Test.new

a.blah # -> 0, 1 or 2

Adding self. to a method name makes the method into a module function, that can be accessed from outside the module.

module Test

  def self.blah

    p rand(3)

  end

end

 

# Is the same as

module Test

  def blah

    p rand(3)

  end

  module_function :blah

end

Then there is access control for your methods:
- Public: Method can be accessed by anything anywhere
- Protected: Method can only be called upon by objects from the same class or sub-classes
- Private: Method can only be called upon by self.

Hope that cleared some things up.

 

[embooglement]

Thank you! Like I said, I don't usually use modules, and wasn't sure of the syntax.

And for the record, I figured out how to get the angle of a line.